1. Field of the Invention
The present invention relates to an apparatus adapted for use in manufacturing printed circuit boards. More particularly, it relates to a printed circuit board laminating apparatus (or laminator) for laminating the surface of the baseboard of a printed circuit board (hereinafter referred to as baseboard or board) with a film, such as dry photoresist film (hereinafter referred to as resist film) or protective film.
2. Description of the Prior Art
Conventionally, the printed circuit board is manufactured by forming a layer of photoresist on the surface of a layer of the conductive material of a baseboard, such as a copper-clad board, and then forming a wiring pattern thereon by a photolithographic technique. In this method, the photoresist layer is formed mainly by laminating a resist film onto the surface of the baseboard.
Conventionally, the lamination of the resist film onto the baseboard is performed in such a manner that a piece of resist film having a length corresponding to that of the board is cut from a long resist film and laminated onto the board. However, this method is inefficient and is not suitable for mass-production procedures.
Accordingly, a laminator which can continuously laminate a long resist film onto boards, without cutting the film, was recently developed. However, this conventional laminator still has the following problems.
Namely, this conventional laminator is constructed in such a manner that the boards are continuously fed, with a gap therebetween, by, for example, feed rollers, while a long resist film is continuously supplied by means of a laminating roll and laminated by thermo-compression onto the surfaces of the boards.
According to this type of laminator, the boards laminated with the resist film are fed out of the laminator while still being interconnected by the resist film. Accordingly, to separate the boards, the resist film must be cut between the boards. Also, the board is usually provided with indexing holes (or pilot holes or adjusting holes) used for positioning the board in subsequent steps of the process. Thus, the resist film must be also provided with access holes to enable access to the indexing holes in the boards.
However, the conventional laminator is not provided with means for cutting the resist film and making the access holes. Accordingly, after the laminating process, the resist film and the access holes must be cut by hand with a knife, or the like. This means that there is no saving in labor, and that without the provision of automation in the printed circuit board manufacturing line, the process is inefficient, and productivity is low. There is a further disadvantage in that the inaccuracy in cutting the resist film and making the access holes and the scraps of the resist film and board which invariably adhere to the resist film lead to errors in the subsequent photolithographing step, which results in inferior quality and thus, a low yield, of the printed circuit boards.
Furthermore, in the laminator as described above, the gap between the boards fed into the laminator from the preceding board-processing section or board accumulator is important. For example, where the gap is too small, the cutting of the resist film after lamination cannot be successfully performed. On the other hand, where the gap is too large, the end portions of the resist film protruding from the board, after being cut, tend to turn or roll over, thereby increasing the disadvantages described above.